With increasing development of information industries and high-tech industries, most precise electronic instruments and facilities need highly reliable power to maintain normal operations. Generally, an uninterruptible power supply (UPS) are widely used to provide stable power to the loads that are connected with the UPS. For example, UPS apparatuses become essential for network communication appliances, data centers and some important information appliances.
The conventional uninterruptible power supply (UPS) comprises a charge circuit and a DC-to-DC converting circuit for providing standby power. In a case that the utility power source is normal, the DC-to-DC converting circuit is disabled but the backup battery of the uninterruptible power supply is charged by the charge circuit. Whereas, in a case that the utility power source is interrupted, the charge circuit is disabled but the storage voltage of the backup battery (e.g. 11V) is converted into the rated voltage of the load (e.g. 12V).
Since the charge circuit and the DC-to-DC converting circuit of the conventional uninterruptible power supply are two independent circuits for charging and discharging the backup battery, the volume of the conventional uninterruptible power supply is bulky. In addition, the conventional uninterruptible power supply has a high component number, complicated circuitry layout and high fabricating cost. Moreover, since the charge circuit and the DC-to-DC converting circuit fail to be simultaneously operated, the circuitry utilization of the conventional uninterruptible power supply is insufficient.
Therefore, there is a need of providing an uninterruptible power supply with an integrated charge/discharge circuit so as to obviate the drawbacks encountered from the prior art.